For the head protection of vehicle occupants, in the case of a vehicle side impact or turnover, inflatable gas bags are employed which in the normal resting position are stowed folded in a slim receiving housing. The receiving housing along with the gas bag stowed therein and an inflator for inflating the gas bag form a module which prior to fitting the roof headlining to the body of the vehicle is arranged on and secured to the border region between roof and vehicle doors.